Tumor extravasation following a cement augmentation procedure for vertebral compression fracture in metastatic spinal disease

Balloon kyphoplasty (BKP) has been proven to be safe and effective in the management of pathological vertebral compression fracture (VCF) due to metastatic spinal disease. The most common serious complications related to BKP include cement extravasation and new fractures at adjacent levels. Although the potential for "tumor extravasation" has been discussed as a potential iatrogenic complication, it has yet to be confirmed. The authors report on 2 cases of tumor extravasation following BKP, which they base on an observed unusual rapid tumor spread pattern into the adjacent tissues. They postulate that by increasing the vertebral body internal pressure and disrupting the tissues during balloon inflation and cement application, a soft-tissue tumor can be forced beyond the vertebral bony boundaries through pathological cortical defects. This phenomenon can manifest radiologically as subligamentous spread and/or extension into venous sinusoids, resulting in epidural venous plexus involvement, with subsequent tumor migration into the adjacent vertebral segments. Accordingly, the authors advise caution in using BKP when significant epidural tumor is present. The complication they encountered has caused them to modify their preference such that they now first use radiosurgery and subsequently BKP to ensure the target is appropriately treated, and they are currently developing possible modifications of procedural technique to reduce the risk.